|Year : 2015 | Volume
| Issue : 1 | Page : 11-19
RK Mishra1, Surajit Bhattachrya2
1 Department of Plastic and Reconstructive surgery, Sushrut Institute of Plastic Surgery, Lucknow, Uttar Pradesh, India
2 Department of Plastic and Reconstructive surgery, Sahara Hospital, Lucknow, Uttar Pradesh, India
|Date of Web Publication||4-Feb-2015|
Dr. R K Mishra
Sushrut Institute of Plastic Surgery, 29, Shahmeena Road, Lucknow - 226 003, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Craniofacial microsomia (CFM) is the second most common craniofacial anomaly treated surgically in craniofacial centers worldwide. This craniofacial condition is variably associated with anomalies of the ears, jaws, orbits, soft tissue of face and function of the facial nerve. It can also be associated with extra-cranial deformities like cervical and rib anomalies. Largely, the etiology of CFM is unknown, but prenatal exposures of some drugs and genetic abnormalities may be associated with the condition. Diagnosis and treatment of CFM is challenging due to a wide spectrum of deformities (both osseous and soft tissue). Depending upon the severity of the deformity a wide variety of surgical treatment plans exist. After treating forty cases of CFM, we experienced that, though the treatment of severe form of CFM is difficult, but a coordinated multi-specialty team approach, especially of Reconstructive plastic surgery, orthognathic surgery, ear, nose and throat specialists leads to a successful and rewarding outcome.
Keywords: Craniofacial microsomia, dysostosis otomandibularis, first and second branchial arch syndrome, goldenhar syndrome, hemifacial microsomia
|How to cite this article:|
Mishra R K, Bhattachrya S. Craniofacial microsomia. J Cleft Lip Palate Craniofac Anomal 2015;2:11-9
| Introduction|| |
Craniofacial microsomia (CFM) is a spectrum of morphogenetic abnormalities involving structures derived from the first and second branchial arches , [Figure 1]. It is the second most common facial birth defect after cleft lip and palate. , Fourteen terms describing this malformation complex can be found in the literature including first and second branchial arch syndrome,  hemifacial microsomia,  dysostosis otomandibularis,  Congenital oto-cephalic syndrome,  auriculo-branciogenic dysplasia,  oto-cranio cephalic syndrome,  and Goldenhar-Gorlin syndrome More Details.  Goldenhar syndrome is a variant of CFM and has cervical (neck) and rib anomalies and epibulbar dermoids [Figure 2]. 
|Figure 1: A case of right sided craniofacial microsomia. The visible deformities are: Microtia and cleft lip/palate, occlusal cant, elevated angle of mouth and deviated chin|
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Paramount to the understanding of CFM is an appreciation of head and neck embryology. Development of the branchial arches, facial growth, and differential craniofacial growth contribute to the formation of the facial structures. All structures derived from the first and second branchial arches - bones, muscles, cranial nerves, organs, and glands can be involved. , The collected group of deformities that make up this syndrome may vary greatly in extent and degree covering a wide spectrum ranging from mild underdevelopment of the lower jaw to severe deformity of the skull and face [[Figure 3]a and b]. Characteristically this deformity, as the name implies (hemifacial), involves one side of the face, however involvement of both sides to some degree can be observed in as high as 15% of all cases [Figure 4]. , The most obvious deformity involves the lower jaw and ear, but soft tissue deficiency, maxillary hypoplasia and even orbit and skull anomalies may also be present.  Lack of development of the external ear is a common feature with the severity of the ear deformity proportional to the jaw deformity.  The parotid can be malformed or missing, auricular and facial nerve abnormalities have been reported in up to 50% of affected children. The presence of hearing loss of varying degrees necessitates otolaryngologic evaluation.  Isolated microtia is now considered a microform of CFM and should prompt thorough evaluation before undertaking cosmetic repairs.  In addition, when there is a significant facial bone hypoplasia, patients can develop airway obstruction called sleep apnea. Untreated, this can lead to poor weight gain, small stature, cerebral hypoxia, and even death.
|Figure 3: Varying degree of deformities in craniofacial microsomia may vary from mildly hypoplastic mandible and microtia (a), to very severe deformity with cleft lip and palate, absent ramus and condyle of mandible, orbital dystopia (b)|
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Most patients with CFM have some degree of mandibular hypoplasia that is seen clinically as a deviated chin [[Figure 3]a], occlusal cant [Figure 5] and an asymmetry in the position of the corners of the mouth  [Figure 1]. Patients with mandibular growth disturbances can present at any age. The challenge in treating many of these patients lies in the variability of age and associated pathology of other facial structures such as the maxilla, the muscles of mastication, and the zygoma. All these elements have a well-orchestrated interplay with one another and, therefore, the type of treatment chosen to address the individual deformity must be specific to the patient's needs.
| Classification|| |
David et al.  propounded the most comprehensive classification from the Australian Cranio-Facial Unit (ACFU) of Adelaide, Australia. Three categories were sought in each patient - skeletal, auricular, and soft tissue.
The five skeletal categories are [[Figure 6]a-e]:
|Figure 6: Various skeletal (S) categories in David et al. classification. S1 - Small mandible of normal shape (a). S2 - Condyle, ramus, and sigmoid notch identifiable but grossly distorted. Mandible strikingly different in size and shape from normal (b). S3 - Mandible severely malformed, ranging from poorly identifiable ramal component to complete agenesis of ramus (c). S4 - S3 mandible + orbital involvement — gross posterior recession of lateral and posterior orbital rims (d). S5 - S4 defect + orbital dystopia, hypoplasia and asymmetrical neurocranium and a flat temporal fossa (e)|
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- S1 - Small mandible of normal shape
- S2 - Condyle, ramus, and the sigmoid notch identifiable but grossly distorted. Mandible strikingly different in size and shape from normal
- S3 - Mandible severely malformed, ranging from poorly identifiable ramal component to complete agenesis of ramus
- S4 - S3 mandible + orbital involvement - gross posterior recession of lateral and posterior orbital rims
- S5 - S4 defect + orbital dystopia, hypoplasia and asymmetrical neuroranium and a flat temporal fossa.
The four auricular categories are [[Figure 7]a-c]:
|Figure 7: Various Auricular categories in David et al. classification. A-1 category (a), A-2 category (b) and A-3 category (c)|
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- A0 - Normal
- A1 - Small malformed auricle, retaining all features
- A2 - Rudimentary auricle, with hook at cranial end corresponding to the helix
- A3 - Malformed lobule + absent rest of pinna.
And the three soft tissue categories are [[Figure 8]a-c]:
|Figure 8: Various soft tissue categories in David et al. classification. T1 - Minimal contour defect with no cranial nerve involvement (a), T2 - Moderate defect (b), T3 - Major defect, obvious facial scoliosis, severe hypoplasia of cranial nerves, parotid, muscles of mastication, eye involvement + facial clefts (c)|
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- T1 - Minimal contour defect with no cranial nerve involvement
- T2 - Moderate defect
- T3 - Major defect, obvious facial scoliosis, severe hypoplasia of cranial nerves, parotid, muscles of mastication, eye involvement + facial clefts.
The classification system of mandibular hypoplasia most frequently used is that of Pruzansky:  Grade-1 mandibles are normal in configuration, but reduced in size [[Figure 3]a]. Grade-2 mandibles demonstrate hypoplasia plus mal-development of the associated condyle and coronoid processes. Kaban et al.  later sub-classified the latter group as either 2a or 2b. Grade-2a mandibles have hypoplastic and malformed condyles, but the condylar head/glenoid fossa spatial relationship is spatially maintained in the sagittal dimension similar to that of the contralateral side. In these patients, the misshapen condyle is functional and can be used in the mandibular reconstruction. Grade-2b mandibles have a severely hypoplastic and malformed condyle, which is displaced outside of the sagittal plane of the contralateral temporomandibular joint (TMJ). These patients frequently have restricted TMJ function. Grade-3 mandibles are severely hypoplastic and lack a condyle, coronoid process and glenoid fossa [[Figure 3]b]. This classification system can be applied to patients with unilateral or bilateral mandibular hypoplasia. Any treatment plan constructed for these patients must factor in the age of the patient and the degree of skeletal hypoplasia in order to optimize long-term results [Table 1].
|Table 1: Surgical treatment plan of craniofacial microsomia based on David et al. classification system|
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Meurman  proposed the first classification scheme for CFM based on auricular findings. Murray et al.  has proposed a new scheme based on skeletal abnormalities, which has proven useful in planning surgical management in this diverse group of patients. Type one patients have small mandibles with normal shape, a normal glenoid fossa and a short mandibular ramus. Type two findings include anteriorly and medially displaced TMJs, a short and abnormally shaped ramus, and an abnormally contoured TMJ cavity. Complete absence of the mandibular ramus and glenoid fossa, no TMJ and the body of the mandible ending at the molar region classifies type three patients.
The other widely used system is the OMENS (O for orbital distortion; M for mandibular hypoplasia; E for ear anomaly; N for nerve involvement; and S for soft tissue deficiency) classification scheme  later modified to the OMENS + to include extracranial manifestations.  The acronym stands for orbit, mandible, ear, nerve, and soft tissue; each feature is assigned a severity score. More recently, a pictorial representation of the OMENS system was introduced  and later modified  to facilitate ease of use.
| Incidence|| |
Craniofacial microsomia has an incidence reported between 1/3500 and 1/26,550 live births. The male to female and right to left sided ratios are both 3:2. Bilateral involvement occurs in roughly 10% of cases. The majority of cases are sporadic with no definite inheritance being proven in the literature. Recurrence risk is consistently reported at 2-3% for subsequent pregnancies.
| Aetiopathology|| |
In a paper published, Poswillo  attributed the development of facial deformities consistent with CFM to disruption of the stapedial artery. The stapedial artery functions as a stopgap vascular channel during days 33-45 of embryologic development. Poswillo fed pregnant rats triazene and pregnant monkeys thalidomide and showed the consistent mal-development of first and second branchial arch structures. Robinson  supported Poswillo's theory by demonstrating carotid flow abnormalities in two and defects-related to vascular disruption in a third child with CFM.
| Preoperative Evaluation|| |
The evaluation of CFM includes a thorough history and physical examination, photographic and cephalometric analysis, and three-dimensional computed tomographic study. Family history of consanguinity, intrauterine exposure to infection and toxins, and problems with delivery should be explored. Physical exam should focus on facial asymmetry as well as on isolated findings consistent with this syndrome. Photographs and cephalometry allow for monitoring of facial symmetry over time and aid in planning surgical approaches to individual patients. Three-dimensional computed tomography provides accurate reconstruction of patients' craniofacial skeletons and alleviates the need for constructing physical models. This allows for faster and more accurate surgical planning.
| Treatment|| |
Treatment of CFM is individualized. Principles basic to all cases include treating bony tissue deficits first, followed by soft tissue augmentation. The mandible is addressed initially since correction of mandibular malformations often stimulates maxillary growth. Maxillary growth is further enhanced with the use of maxillary activators. Costochondral grafts , must be used in TMJ reconstructions. Soft tissue deficits are corrected with local and microvascular free flaps.  Facial nerve defects usually are permanent and can be managed accordingly by tendon or muscle transfer.  Hearing must be assessed early to allow for hearing augmentation. Reconstruction of middle ear structures is often delayed until craniofacial reconstruction is complete. 
The UCLA Craniofacial Clinic Protocol and the ACFU Protocol  are aimed at maximizing results and minimizing the number of procedures. The timing and types of procedures may vary depending on the severity of the deformity and the individual patient. In general, corrections include many of the following:
- Preauricular skin tags (age under 1 year): Excision;
- Macrostomia or wide mouth (age under 1 year): Commisuroplasty;
- Mandibular hypoplasia (5-8 years of age): Internal distraction osteogenesis is used to lengthen the lower jaw (for severe cases with absence of mandibular condyle and ramus, a rib graft may be necessary) ,
- External ear deformity or absence (6-8 years of age): Staged ear reconstruction [[Figure 9]a-d] with a rib graft framework, elevation, lobule (ear lobe) and tragus (front of ear) reconstruction are performed ,,
- Orbital dystopia (asymmetric eyes) (6-11 years of age): Although rarely required, repositioning of the orbit and/or advancement of the forehead and brow (fronto-orbital advancement) may be performed.
- Jaw asymmetry (15-18 years or age of skeletal maturity): Preoperative orthodontics, followed by jaw (orthognathic) surgery with Le Fort I (upper jaw) and mandibular sagittal-split (lower jaw) osteotomies are often necessary. 
- Soft tissue asymmetry (after jaw surgery): Final facial contouring with autogenous fat grafting, dermal fat grafts or even a fascial-fat free flap from the upper back are often necessary after other corrections.
|Figure 9: Staged ear reconstruction of microtia (a) using costo-chondral graft framework (b). Final result after lobule transposition and elevation (c and d)|
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Distraction has the advantage over other techniques in that it requires minimal operative time, carries little risk, minimizes hospitalization time, obviates the need for blood transfusion, bone graft and intermaxillary fixation, and has minimal relapse rates. Patients who require only unidirectional lengthening and have adequate mandibular bone stock are ideal candidates for intraoral distraction [[Figure 10]a]. Patients with severe mandibular deficiencies and require distraction in multiple dimensions are best treated with a multi-planer extraoral device. In addition, patients who have previous external scars from other procedures are treated with an extraoral device. Since multi-planer extra oral devices are costlier and not easily available, double osteotomy along with two uni-planer simple distractors can be used simultaneously with a central common pin to gain distraction in two planes [Figure 10]b and c]. With an extraoral approach, care is taken not to damage soft tissue that may be needed for future surgeries, such as external ear remnants or microvascular soft tissue augmentation.
|Figure 10: Variety of intraoral mandibular distractor devices available in the market (a). Extraoral bi-planer mandibular distraction achieved by using two uni-planer distractors to distract ramus in vertical plane and body in horizontal plane. Frontal (b) and lateral (c) view|
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The site and direction of the osteotomy is based solely on the bony pathology as well as the position of tooth follicles. The vector of the distraction is also a variable. Distraction can occur in the vertical, horizontal, or oblique vectors (based on the relationship of the vector to the long axis of the mandibular body).  A vertical vector of distraction is preferred for lengthening a deficient ramus in a vertical dimension or for transporting the condyle up into the glenoid fossa. The horizontal vector along the long axis of the mandible is chosen in order to lengthen the mandible in a purely horizontal plane, as in bilateral micrognathias whose deficiency is predominately in the mandibular body. If an oblique vector (a direction between the vertical and horizontal vectors) is chosen, the osteotomy is placed anterior to the coronoid in order to prevent impingement of the coronoid on the zygomaticomaxillary buttress during distraction. An oblique distraction vector not only lengthens, but also vertically elongates the mandible. Before converting the corticotomy into an osteotomy, the screws or pins are placed.
After a delay of 5-7 days (termed the latency period), distraction commences at a rate of 0.5 mm twice daily (termed the activation phase). This rate is continued until the mandibular length is overcorrected by several millimeters. During distraction, the vertical or oblique vector will typically become more horizontal, due to the counterclockwise pull of the muscles of mastication. At this time orthodontic intermaxillary elastics may be used to mold the regenerating bone and optimize the occlusion (termed molding the regenerate). The device is left in place to serve as an external fixator for 8 or more weeks, until there is radiographic evidence of mineralization. This stage is known as the consolidation phase.
In patients with unilateral CFM undergoing distraction, it is important that a dental impression be taken and a bite block placed in the surgically created posterior open bite when the device is removed. This will allow the orthodontist to level the maxillary occlusal plane by allowing for eruption of the ipsilateral maxillary dento-alveolar complex. Distraction will also affect the entire facial milieu: The soft tissue envelope bulk will increase due to a combination of soft tissue expansion and muscle hypertrophy and leveling of the oral commissure are usually noted.
Age is also a factor in developing a treatment plan. Under 2 years of age, mandibular distraction is not usually performed because it is difficult to identify tooth buds at this age, and therefore permanent dental injury is a likely occurrence. Second, distraction at this age can be a daunting experience for the patient and the parents. The exception to this would be when early mandibular distraction is used to prevent tracheotomy in a newborn with micrognathia that is causing severe airway obstruction.
Huisinga-Fischer et al.  observed for longitudinal results of mandibular distraction and found that in around 50% of the cases, there seems to be a relapse occurring 1-year after distraction osteogenesis, and this relapse has a progressive character.
Meazzini et al.,  Suh et al.,  and Sakamoto et al.  reported improvement of symmetry, occlusal cant and mandibular length and height resulting into satisfied patients after distraction osteogenesis of mandible. However, they also mention that distraction osteogenesis starting after 5-years of age did not influence the maxillary skeletal base. They all reported that mandibular vertical changes showed a gradual return of the asymmetry with growth in all patients probably due to genetically determined craniofacial growth patterns.
Final orthognathic surgery and free composite tissue transfer
Children with S3, S4, and S5 (absent ramus, condyle, and/or glenoid fossa), are initially treated with an autogenous costochondral rib graft reconstruction at approximately 3-4 years of age (first stage). The costochondral graft will increase mandibular length, reconstruct the condyle, and form a pseudoarthrosis with the glenoid fossa. In a second stage, at least 6 months after removal of the fixation, distraction of the rib graft can be performed.  At the time of skeletal maturity however microvascular free tissue transfer is offered to create absent parts of the mandible [[Figure 11]a-c] as well as correction of orbital rim deformities using addition of rib grafts. 
|Figure 11: Reconstruction of right mandible (S3 T3) in a severe case of craniofacial microsomia using microvascular free fibula flap in a teenager. Preoperative clinical picture and three-dimensional scan showing severe deformity of mandible with absent ramus (a). Intraoperative picture (b), and postoperative picture showing good facial symmetry and survival of reconstructed mandible (c)|
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Tanna et al.  compared the effectiveness of free tissue transfer and staged fat grafting in case of CFM. He reported that the mean number of procedures was less for the free tissue transfer cohort without any significant complication. Rahpeyma et al.  suggested preoperative evaluation of facial artery and anterior belly of the digastric muscle are essential steps for success in free tissue transfer. Furthermore, bone suture technique, especially hitching the soft tissue with fixed bony points, helps achieve more predictable results and reduces the need for postoperative bulky dressing. Based on the composition of the flap, it can be used as a myocutaneous, faciocutaneous, and osteomuscular flap. Free flaps are difficult procedures and can have considerable complications. The complications of free tissue transfer may be immediate (vascular compromise - venous/arterial, hematoma, bleeding), delayed (facial asymmetry, malocclusion, implant failure and malunion, donor site morbidities) and very late (sagging of the flap, color mismatch, altered sensation, bulky flap during weight gain periods).
During free tissue transfer, avoid muscle (as de-neurotized muscle atrophies to a thin sheet) and prefer dermis and fat with as small as skin pedicle possible, preferably as pre-auricular skin strip. The side burn should be taken into consideration.
When the glenoid fossa is absent, a new one is constructed with rib grafts fixated to the zygomatic arch. From age 6 to the teen years, during the period of mixed dentition, orthodontic treatment is needed to promote growth of the affected dentoalveolus and to aid in the proper eruption of the permanent teeth. Indications for surgery in the teen years include:
- Residual postsurgical skeletal deficiency due to surgical relapse or abnormal growth,
- Unsatisfactory bone contour,
- Malocclusion, or
- Absence of previous treatment.
Any appropriately chosen maxillofacial surgical procedure could be performed during this time ranging from sagittal split osteotomies, to bone grafting, to distraction. In patients with minimal mandibular deformities, classic orthognathic procedures are indicated. Mandibular distraction should be considered in patients with moderate to severe skeletal deficiency, or bilateral disease, in whom pressure from the soft tissues would significantly increase the risk of postoperative graft resorption or skeletal relapse.
Restricted mandibular growth is frequently associated with abnormal maxillary development. The ipsilateral maxilla and dento-alveolar processes are often deficient in the vertical dimension. In mild cases this can be treated with a bite block and orthodontic therapy as described above; however, in more severe circumstances a maxillary (Le Fort I) leveling procedure may be considered. Traditionally, this has involved a Le Fort I osteotomy followed by ipsilateral lengthening of the mandible with bone grafts and a contralateral impaction. The deficient maxilla can be distracted in conjunction with the mandible. In this technique, a Le Fort I corticotomy is made at the time of the mandibular osteotomy and placement of the distraction device. The upper and lower jaws are wired into intermaxillary fixation. After a 5-day latency period, distraction is commenced at the rate of 1 mm/day. At the conclusion of maxillary/mandibular distraction, the device is left in place for 8 weeks to allow for bone consolidation. Using this technique, we have had excellent soft tissue and bony results with complete leveling of the dental occlusion. Intermaxillary fixation is not employed during the latency period; instead heavy guiding elastics are placed at the time of distraction. The bands are modified throughout the process to obtain optimal dental alignment.
Ancillary procedures to achieve facial symmetry
Nonvascularized dermis fat graft and lipo-filling are the simplest methods mentioned in literature for the treatment of soft tissue deformity or asymmetry in CFM. , Obviously, lipo-filling is much simpler but with great resorption rates and the need for procedure repetition. To achieve facial symmetry in unilateral cases some ancillary procedure is usually required in the form of sliding genioplasty and/or autologous fat grafting. Autologous fat grafting is usually needed in the cheek and mandibular margin area to correct minor discrepancies. Tanna et al.  reported that serial fat grafting provided a useful alternative to microvascular free tissue transfer after skeletal reconstruction. Although the mean number of procedures was less for the microvascular free flap group versus the fat grafting group (2.2 vs. 4.3), the combined surgical time was greater for the microvascular free flap group. The volume of soft tissue implanted and symmetry rating was 20-25% higher in microvascular group than fat grafting group, but the complication rate was also higher for the microvascular free flap group than that for the fat grafting group. No statistically significant difference in patient or physician satisfaction was noted. We usually harvest fat from lower abdomen or medial thigh, allow it to sediment for 30-40 min. The fat is mixed with autologous platelet rich plasma activated with calcium just before injection into the required and marked area to achieve better take of fat and good results [Figure 12].
|Figure 12: A case of left sided craniofacial microsomia with facial asymmetry. Autologous fat graft mixed with activated autologous platelet rich plasma over the left cheek, zygomatic area and mandibular margin to improve facial asymmetry|
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| Summary|| |
Craniofacial microsomia is a syndrome with diverse presentation. The majority of cases are sporadic with stapedial artery disruption being considered the most likely etiology. The ACFU classification based on skeletal, external ear, and soft tissue abnormalities is most comprehensive and treatment specific. Treatment schemes are adapted to the specific dysmorphology of individual patients. Distraction histiogenesis, orthognathic surgeries, composite free tissue transfer along with good preoperative and postoperative orthodontics and timely reconstruction of external ear and other facial clefts and soft tissue blemishes completes the treatment.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]